What research issues concerning fMRI are more important to the psychologist than to the neurosurgeon? In your response, find and describe an example of psychological research that is investigated with fMRI. (answer in atleast 100 words and repsond to student)

Student 1:

What research issues concerning fMRI are more important to the psychologist than to the neurosurgeon? In your response, find and describe an example of psychological research that is investigated with fMRI.

Functional Magnetic Renonance Imaging differs from the MRI because it is sensitive to brain activity. Psychologist would find this more important because this allows them the opportunity to measure the patterns and fluctuations of neural activity. This could especially be helpful for patients with mental disabilities of some sort who are unable to effectively communicate their thoughts or feelings. This device would practically allow their minds to be read.

According to an article from Chicago University's psychology department, an fMRI can be a useful tool for comparing psychological theories that predict the same behavioral outcomes, but differ in the hypothesized mechanism explaining the outcome (e.g., Dickhaut et al., 2003). An example of this would be a psychological research on how do people make decisions. The fMRI could record the brain activity of various individuals and compare and contrast the data to determine the answer.

Question 2:

Heirarchy of the Visual System

Our visual system functions as a hierarchy of information, starting with tiny pieces of visual information about light in the retina, to specific types of objects and scenes in the cortex. Seeing seems so effortless for us, but what's really happening is an almost unbelievably complex transformation of light to a visual scene. It begins in the retina, which sends information to LGN, which relays the signal to the primary visual cortex, which then sends information to the “higher” visual association cortex. (Note that the primary visual cortex is called other things too; it’s also known as the striate cortex, visual area 1 (V1 for short), and Brodmann’s Area 17.) Beyond the primary visual cortex, the visual processing stream splits into two pathways: the ventral (what?) pathway and the dorsal (where and how?) pathway. So here we go....

In the dark our photoreceptors are always “on”. They are in a depolarized state with the sodium channels open, and constantly release a neurotransmitter that inhibits bipolar cells and makes them inactive. When a rod or cone absorbs light it closes the sodium channels in the membrane, which make it stop releasing its neurotransmitter, which disinhibits the bipolar cells that the photoreceptor is connected to. Then the bipolar cells can excite the ganglion cells "normally". The release of neurotransmitter in the dark is called the “dark current”. You can get the whole story here.

The sensory information received by the photoreceptors has a long way to travel (well, from their point of view) to get from the front of the head to the back of the head. After information about the visual scene is received by the photoreceptors, it is passed along by bipolar and other cells to the ganglion neurons within the retina. The axons of the ganglion neurons collect at the optic chiasm (which is why you have a blind spot) and leave the eye. Some of the axons cross over at the optic chiasm. It’s important to remember that not all axons cross over. It’s common to think that the left hemisphere gets information from the right eye ……wrong! The left hemisphere receives information from the right visual field, which is the visual scene in the environment, not in the eye. Remember that the lens completely inverts the image, so information from the right visual field lands on the left half of our retina.

First Stop: LGN

The lateral geniculate nucleus (LGN) of the thalamus is where the gangion axons from the retina end up. There is one LGN on each side of the thalamus. The thalamus acts as a relay station to the cortex.

In the LGN, visual information is mapped into six orderly layers that retains the visual information detected in the retina. The magnocellular, parvocellular, and koniocellular layers of the (LGN) are part of the “M”, “P”, and “K” pathways or channels, named after magnocellular, parvocellular, and koniocellular pathways that begin with ganglion cells in the retina. The M layers get most of their input from the rods, and are important for detection of movement. The P and K layers get most of their input from the cones, and are important for detecting detail and color. The P pathway carries information from red and green cones, while the K channel carries information from blue cones. Information from each layer is then transferred to the cortex.

Next Stop: The Primary Visual Cortex

The visual cortex integrates information about spots of light and puts them together into larger features that represent our visual environment. Nobel prize winners Hubel and Weisel found that neurons in the retina and LGN fired in response to spots of light, but neurons in the primary visual cortex did not fire. By accident they discovered that the primary visual cortex neurons respond to lines in specific orientations, which result in our ability to detect edges that we see. You can see an example Hubel and Wiesel’s cat experiments here: YouTube - Hubel and Wiesel Cat Experiment. Hubel is also in this short video about vision research here: YouTube - Hubel's research .

Hubel and Weisel pioneered the discovery of edge detectors in the primary visual cortex. These days, after additional discoveries by DeValois and others, vision researchers use the concept of spatial frequency, which is the number of light-dark transitions that occur within a single degree of visual angle.

Visual angle is used a unit, because perceived detail of an object changes with distance. A set of light and dark bands will look thinner (higher spatial frequency) farther away, and larger (lower spatial frequency) closer up. Using the visual angle makes the distance between the bars constant, because it’s based on the inside of the eye. Think of the eye as a globe that can be subdivided into 360 degrees of curvature. Distance across the retina can be described in degrees and minutes of retinal arc. A single degree of visual angle is generally close to the finest detail we can discriminate. If you look at your thumb after stretching your arm in front of you, the retinal image of your thumb will cover about two degrees of arc, or two degrees of visual angle.

The primary visual cortex creates a map of our visual field, but this basic information is transferred to the “higher” visual association areas described on p. 255 in the Vision chapter -- with areas labeled V2, V3, V4, V5, MT and so on. Here, information from the primary visual cortex is integrated and interpreted in ways that are meaningful to us, by providing a context for the features we see. Each area performs a separate function, as can be seen by lesions to these areas that result in specific impairments in vision and behavior.

Here are the questions (please answer all 3; a few sentences each should be enough):

On p. 255 of the Vision chapter, the authors describe specialized brain areas for recognizing different types of objects and information in our environment. What might happen if one of these areas becomes damaged? Using links provided above (in the Effects of Brain Damage section), or your own Google/internet search, see if you can find a webpage or website on the internet that describes what happens when a specific brain area is damaged. (Make sure the information is credible!). For this question, name and describe the area that is damaged, and the visual impairment it causes. Describe how the brain damage in this area leads to the impairment that it does. Don’t forget to share the link you used with your classmates.

How do you know that the color red is red? What makes this color red? Do you experience red the same way as everyone else? If we traveled to another planet where the environment was composed of a very difficult chemical composition, would we see new colors?

What do you not understand, or are confused about, from the Vision chapter? Or, was there anything that you did not know or was surprising about vision before reading the chapter and viewing the links above?

Student 2:

1. On p. 255 of the Vision chapter, the authors describe specialized brain areas for recognizing different types of objects and information in our environment. What might happen if one of these areas becomes damaged? Using links provided above (in the Effects of Brain Damage section), or your own Google/internet search, see if you can find a webpage or website on the internet that describes what happens when a specific brain area is damaged. (Make sure the information is credible!). For this question, name and describe the area that is damaged, and the visual impairment it causes. Describe how the brain damage in this area leads to the impairment that it does. Don’t forget to share the link you used with your classmates.

Capgras- this disease can cause changes in brain chemistry associated with mental illness, or a physical trauma to the brain. Both result in a disconnect between the brain’s visual cortex and emotional recognition. This is why it is often referred to as “the imposter syndrome”. The person suffering from Capgras can recognize an individuals voice on the phone, but in person there is no recognition. The person suffering from Capgras has no visual impairment, but the part of the amygdala that processes memory and reaction that is linked to vision is damaged.

2. How do you know that the color red is red? What makes this color red? Do you experience red the same way as everyone else? If we traveled to another planet where the environment was composed of a very difficult chemical composition, would we see new colors?

As humans, our visual system is equipped with 3 types of cones: S cones, M cones, and L cones, which allow us to see blue, green, and red. Although recent research has discovered that some women are equipped with 4 types of cones. It would be difficult to say whether I experience red the same way as everyone else, since research has shown a cultural difference in color perception. Since our visual system has been an adaptation for survival, I think that it would be possible for our color system to change in a new environment if necessary, but it would take time being exposed to evolve.

(pg. 257-259 of Textbook: Biological Basis of Behavior)

3. What do you not understand, or are confused about, from the Vision chapter? Or, was there anything that you did not know or was surprising about vision before reading the chapter and viewing the links above?

Luckily this isn’t my first time studying the anatomy of the visual system. It was interesting to learn about its connection to the brain, and how different diseases can cause a disconnect between vision and recognition. I also found it interesting that women are already developing types of cones. It makes me wonder whether this adaptation will continue through future generations.